PIC18F4685-I/PT Microchip Technology, PIC18F4685-I/PT Datasheet - Page 110

• Manufacturer Part Number: PIC18F4685-I/PT
• Description: IC PIC MCU FLASH 48KX16 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F4685-I/PT

• Program Memory Type: FLASH
• Program Memory Size: 96KB (48K x 16)
• Package / Case: 44-TQFP, 44-VQFP
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: CAN, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 36
• Eeprom Size: 1K x 8
• Ram Size: 3.25K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 3328 B
• Interface Type: EUSART, I2C, MSSP, SPI
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 36
• Number Of Timers: 4
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 11 Channel
• Package: 44TQFP
• Device Core: PIC
• Family Name: PIC18
• Maximum Speed: 40 MHz
• Operating Supply Voltage: 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT44PT3 - SOCKET TRAN ICE 44MQFP/TQFPI3-DB18F4680 - BOARD DAUGHTER ICEPIC3AC164305 - MODULE SKT FOR PM3 44TQFP444-1001 - DEMO BOARD FOR PICMICRO MCUAC164020 - MODULE SKT PROMATEII 44TQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F2682/2685/4682/4685
7.6
Data EEPROM memory has its own code-protect bits in
Configuration
operations are disabled if code protection is enabled.
The microcontroller itself can both read and write to the
internal Data EEPROM, regardless of the state of the
code-protect Configuration bit. Refer to Section 24.0
“Special Features of the CPU” for additional
information.
7.7
There are conditions when the device may not want to
write to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been implemented. On power-up, the WREN bit is
cleared. In addition, writes to the EEPROM are blocked
during
parameter 33).
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch or software malfunction.
EXAMPLE 7-3:
DS39761C-page 110
Loop
Operation During Code-Protect
Protection Against Spurious Write
the
CLRF
CLRF
BCF
BCF
BCF
BSF
BSF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BTFSC
BRA
INCFSZ EEADR, F
BRA
INCFSZ EEADRH, F
BRA
BCF
BSF
Power-up
Words.
EEADR
EEADRH
EECON1, CFGS
EECON1, EEPGD
INTCON, GIE
EECON1, WREN
EECON1, RD
55h
EECON2
0AAh
EECON2
EECON1, WR
EECON1, WR
$-2
LOOP
LOOP
EECON1, WREN
INTCON, GIE
DATA EEPROM REFRESH ROUTINE
External
Timer
read
period
; Start at address 0
;
; Set for memory
; Set for Data EEPROM
; Disable interrupts
; Enable writes
; Loop to refresh array
; Read current address
;
; Write 55h
;
; Write 0AAh
; Set WR bit to begin write
; Wait for write to complete
; Increment address
; Not zero, do it again
; Increment the high address
; Not zero, do it again
; Disable writes
; Enable interrupts
and
(T
PWRT
write
,
7.8
The data EEPROM is a high-endurance, byte address-
able array that has been optimized for the storage of
frequently
variables or other data that are updated often).
Frequently changing values will typically be updated
more often than specification D124. If this is not the
case, an array refresh must be performed. For this
reason, variables that change infrequently (such as
constants, IDs, calibration, etc.) should be stored in
Flash program memory.
A simple data EEPROM refresh routine is shown in
Example 7-3.
Note:
Using the Data EEPROM
If data EEPROM is only used to store
constants and/or data that changes rarely,
an array refresh is likely not required. See
specification D124.
changing
© 2009 Microchip Technology Inc.
information
(e.g.,
program